I don't know about the spleen, but that doesn't sound normal.
As to lymph nodes, they often swell when the body is resisting a virus. Mine and my daughter's nodes under our jawline like to swell if there is a virus going around that we have been exposed to. It will often be much bigger for awhile and sometimes just go away - our bodies successfully fought the virus and we didn't get sick. Other times, they stay big and we do get sick. Once we are well, the nodes seem to be smaller.
Hope all goes well for your little one. I'd be much more worried about the spleen.